I highly recommend Gerd's place. Great location, helpful host and modern, attractive apartment. The pool is very clean and the gym is sufficient for a light workout. Right next door is the Four Points Sheraton so you can wave at people paying a lot more for the same location. Extra bonuses are:
+ Across the street in the bottom of Robinson's is a 24 hour supermarket.
+Just as you turn right out of the apartment gate, there is a food stall run by a husband and wife (I assume) team. They have pots of Thai dishes. Everything I had was very tasty and only cost $1 for a bowl of rice and two dishes.
+ If you are exploring Bangkok, Asoke is probably the most convenient spot because it has stops for both the skytrain and the subway.